Experimental study on reduction of scouring and tsunami energy through a defense system consisting a seaward embankment followed by vertically double layered vegetation

OCEAN ENGINEERING

卷:234

Article

Rahman, Md Abedur¹  Tanaka, Norio^1,2  Reheman, Nijati¹ 

[1] Saitama Univ, Grad Sch Sci & Engn, Sakura Ku, 255 Shimo Okubo,Sakura Ku, Saitama 3388570, Japan

[2] Saitama Univ, Int Inst Resilient Soc, Sakura Ku, 255 Shimo Okubo, Saitama 3388570, Japan

关键词: Sea embankment;    Tsunami overflow;    Erosion;    Scour;    Coastal forest;    Energy loss;   

DOI  :  10.1016/j.oceaneng.2021.108816

来源: Elsevier

【 摘 要 】

To countermeasure the scouring and tsunami energy reduction, this study conducted a series of laboratory experiments where vertically double layered vegetation (VDLV) was introduced behind the seaward embankment on a gravel bed. The experimental results demonstrated that the overtopping flow from the embankment experienced a submerged hydraulic jump over the embankment, against all the considered cases. The dense VDLV i.e. dense (G/d = 0.041, where G is the clear gap between the cylinders in the cross-stream direction, and d is the cylinder diameter) short submerged vegetation (L1) incorporated within a sparse (G/d = 2.125) tall emergent vegetation (L2) influenced the scour phenomena. It reduced the relative scoured depth by approximately 29 - 41% at the embankment toe, the maximum scoured depth by approximately 29 - 37%, and the scoured length by approximately 28 - 34%, as compared to that of single embankment system. Furthermore, dense VDLV provided the maximum i.e. 49 - 53%, loss to the total flow energy. The increase in the density of L1 in VDLV offered a larger drag to the flow by shifting the position of the submerged hydraulic jump more towards the embankment top; hence, consequently resulted in significant reduction of scoured depth, scoured length and energy of the tsunami flow.

【 授权许可】

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